Blood type O may increase death risk due to trauma: study

Severe trauma patients with blood type O may have an increased risk of death, according to a study that involved over 900 Japanese emergency care patients.

Researchers at Tokyo Medical and Dental University Hospital, Japan found that severe trauma patients with blood type O had a death rate of 28 per cent, compared to a rate of 11 per cent in patients with other blood types.

"Recent studies suggest that blood type O could be a potential risk factor for hemorrhage (bleeding in large quantities)," said Wataru Takayama, corresponding author of the study published in the journal Critical Care.

"Loss of blood is the leading cause of death in patients with severe trauma but studies on the association between different blood types and the risk of trauma death have been scarce. We wanted to test the hypothesis that trauma survival is affected by differences in blood types," said Takayama.

Patients with blood type O have been shown to have lower levels of von Willebrand factor, a blood clotting agent, than those with other blood types.

Lower levels of von Willebrand factor may be linked to higher levels of haemorrhage.

The researchers suggest that a lower level of the factor is a possible explanation for the higher death rate in trauma patients with blood type O.

"Our results also raise questions about how emergency transfusion of O type red blood cells to a severe trauma patient could affect homeostasis, the process which causes bleeding to stop, and if this is different from other blood types," Takayama said.

"Further research is necessary to investigate the results of our study and develop the best treatment strategy for severe trauma patients," he said.

The researchers used data from medical records of 901 patients with severe trauma who had been transported to either of two tertiary emergency critical care medical canters in Japan during 2013 to 2016.

They caution that all the patients whose data was analysed in this study were Japanese and therefore there is a need for further research to understand if the findings apply to other ethnic groups.

There was no evaluation of the impact of the individual blood types A, AB or B on severe trauma death rates.